Positive electrode, electrochemical apparatus, and electronic apparatus

Abstract

A positive electrode, including a positive electrode current collector and a positive electrode active substance layer, where the positive electrode active substance layer is located on at least a part of one surface or two surfaces of the positive electrode current collector, the positive electrode active substance layer includes a positive electrode material, and the positive electrode material includes element Li; and when a mass percentage of element Li of the positive electrode in the positive electrode active substance layer as tested using an inductively coupled plasma spectrometer (ICP) ranges from 1.45% to 1.55%, an integral intensity of CO2 obtained by testing the positive electrode using a differential electrochemical mass spectrometry is Q≤2000 nmol/mg. This application can improve high-temperature cycling performance and safety of the electrochemical apparatus.

What is claimed is: 
     
         1 . A positive electrode, comprising:
 a positive electrode current collector and a positive electrode active substance layer located on at least a part of one surface or two surfaces of the positive electrode current collector, the positive electrode active substance layer comprises a positive electrode material, and the positive electrode material comprises element Li; and   when a mass percentage of element Li of the positive electrode in the positive electrode active substance layer as tested using an inductively coupled plasma spectrometer (ICP) ranges from 1.45% to 1.55%, an integral intensity of CO 2  obtained by testing the positive electrode using a differential electrochemical mass spectrometry is Q≤2000 nmol/mg.   
     
     
         2 . The positive electrode according to  claim 1 , wherein
 the positive electrode material comprises LiNi x Co y M1 1-x-y-z M2 z O 2 ,   wherein 0.5<x<1, 0≤y<0.5, and 0≤z≤0.005; M1 comprises at least one of Mn or Al; and M2 comprises at least one of Mg, Ti, Zr, Ce, Sr, Y, Hf, Ba, Nb, V, Al, Ge, Sn, W, Mo, Si, or B.   
     
     
         3 . The positive electrode according to  claim 1 , wherein
 the positive electrode material contains element Zr and element B, and a mass percentage of element Zr in the positive electrode material is greater than or equal to that of element B.   
     
     
         4 . The positive electrode according to  claim 1 , wherein
 the positive electrode material comprises primary particles and secondary particles, wherein D v 50 of the secondary particles is greater than 1.5 times D v 50 of the primary particles, wherein   a full width at half maximum FWHM1 of a diffraction peak of plane (003) in an X-ray diffraction spectrum of the secondary particles satisfies 0.140°≤FWHM1≤0.25°; and   a full width at half maximum FWHM2 of a diffraction peak of plane (003) in an X-ray diffraction spectrum of the primary particles satisfies 0.12°≤FWHM2≤0.19°.   
     
     
         5 . The positive electrode according to  claim 1 , wherein
 the positive electrode material comprises primary particles, wherein   an average particle size of the primary particles ranges from 1.5 µm to 2.5 µm.   
     
     
         6 . The positive electrode according to  claim 1 , wherein
 a coating weight of the positive electrode active substance layer ranges from 0.78 g/m 2  to 1.62 g/m 2 , and a compacted density of the positive electrode active substance layer ranges from 3.1 g/cm 3  to 3.55 g/cm 3 .   
     
     
         7 . The positive electrode according to  claim 1 , wherein an elongation of the positive electrode material is less than or equal to 1%. 
     
     
         8 . An electrochemical apparatus, comprising a positive electrode, an electrolyte, a negative electrode, and a separator, wherein the separator is located between the positive electrode and the negative electrode, wherein the positive electrode comprises:
 a positive electrode current collector and a positive electrode active substance layer located on at least a part of one surface or two surfaces of the positive electrode current collector, the positive electrode active substance layer comprises a positive electrode material, and the positive electrode material comprises element Li; and   when a mass percentage of element Li of the positive electrode in the positive electrode active substance layer as tested using an inductively coupled plasma spectrometer (ICP) ranges from 1.45% to 1.55%, an integral intensity of CO 2  obtained by testing the positive electrode using a differential electrochemical mass spectrometry is Q≤2000 nmol/mg.   
     
     
         9 . The electrochemical apparatus according to  claim 8 , wherein
 the positive electrode material comprises LiNi x Co y M1 1-x-y-z M2 z O 2 ,   wherein 0.5≤x<1, 0≤y<0.5, and 0≤z≤0.005; M1 comprises at least one of Mn or Al; and M2 comprises at least one of Mg, Ti, Zr, Ce, Sr, Y, Hf, Ba, Nb, V, Al, Ge, Sn, W, Mo, Si, or B.   
     
     
         10 . The electrochemical apparatus according to  claim 8 , wherein
 the positive electrode material contains element Zr and element B, and a mass percentage of element Zr in the positive electrode material is greater than or equal to that of element B.   
     
     
         11 . The electrochemical apparatus according to  claim 8 , wherein
 the positive electrode material comprises primary particles and secondary particles, wherein D v 50 of the secondary particles is greater than 1.5 times D v 50 of the primary particles, wherein   a full width at half maximum FWHM1 of a diffraction peak of plane (003) in an X-ray diffraction spectrum of the secondary particles satisfies 0.140°≤FWHM1≤0.25°; and   a full width at half maximum FWHM2 of a diffraction peak of plane (003) in an X-ray diffraction spectrum of the primary particles satisfies 0.12°≤FWHM2≤0.19°.   
     
     
         12 . The electrochemical apparatus according to  claim 8 , wherein
 the positive electrode material comprises primary particles, wherein   an average particle size of the primary particles ranges from 1.5 µm to 2.5 µm.   
     
     
         13 . The electrochemical apparatus according to  claim 8 , wherein
 a coating weight of the positive electrode active substance layer ranges from 0.78 g/m 2  to 1.62 g/m 2 , and a compacted density of the positive electrode active substance layer ranges from 3.1 g/cm 3  to 3.55 g/cm 3 .   
     
     
         14 . The electrochemical apparatus according to  claim 8 , wherein an elongation of the positive electrode material is less than or equal to 1%. 
     
     
         15 . The electrochemical apparatus according to  claim 8 , wherein at least one of the following conditions (a) and (b) is satisfied:
 (a) the N-th cycle is present during cycling of the electrochemical apparatus at 45° C., wherein N>400, a capacity retention rate P(N-3) after the (N-3)-th cycle and a capacity retention rate P(N+3) after the (N+3)-th cycle satisfy P(N-3)-P(N+3)>10%, and a volume swelling rate of the electrochemical apparatus after the N-th cycle is less than 10%; and   (b) the electrolyte comprises a multi-nitrile compound, wherein the multi-nitrile compound comprises at least one of 1,3,6-hexanetricarbonitrile, 1,2,6-hexanetricarbonitrile, 1,3,5-pentanetricarbonitrile, 1,2,3-tris(2-cyanoethoxy)propane, succinonitrile, or adiponitrile, wherein a mass ratio of the positive electrode material to the multi-nitrile compound is 1:(0.001 to 0.005).   
     
     
         16 . An electronic apparatus, comprising an electrochemical apparatus, the electrochemical apparatus comprises a positive electrode, an electrolyte, a negative electrode, and a separator, wherein the separator is located between the positive electrode and the negative electrode, wherein the positive electrode comprises:
 a positive electrode current collector and a positive electrode active substance layer located on at least a part of one surface or two surfaces of the positive electrode current collector, the positive electrode active substance layer comprises a positive electrode material, and the positive electrode material comprises element Li; and   when a mass percentage of element Li of the positive electrode in the positive electrode active substance layer as tested using an inductively coupled plasma spectrometer (ICP) ranges from 1.45% to 1.55%, an integral intensity of CO 2  obtained by testing the positive electrode using a differential electrochemical mass spectrometry is Q≤2000 nmol/mg.   
     
     
         17 . The electronic apparatus according to  claim 16 , wherein at least one of the following conditions (a) and (b) is satisfied:
 (a) the N-th cycle is present during cycling of the electrochemical apparatus at 45° C., wherein N>400, a capacity retention rate P(N-3) after the (N-3)-th cycle and a capacity retention rate P(N+3) after the (N+3)-th cycle satisfy P(N-3)-P(N+3)>10%, and a volume swelling rate of the electrochemical apparatus after the N-th cycle is less than 10%; and   (b) the electrolyte comprises a multi-nitrile compound, wherein the multi-nitrile compound comprises at least one of 1,3,6-hexanetricarbonitrile, 1,2,6-hexanetricarbonitrile, 1,3,5-pentanetricarbonitrile, 1,2,3-tris(2-cyanoethoxy)propane, succinonitrile, or adiponitrile, wherein a mass ratio of the positive electrode material to the multi-nitrile compound is 1:(0.001 to 0.005).